Team:DTU-Denmark/Experiments

Experiments

If you've ever participated in iGEM, then you know just how many hours have been spend in the lab. Even though we didn't quite install half a dozen beds in the break room like we wanted to, we still felt like sharing our experiences with all of you. Behold! Our protocols.

Protocols

This protocol is the adapted protocol from 223.

Materials

  • Fungal plates (either streaked or 3-point)
  • Drigalski spatula
  • 500 ml shake flasks
  • Counting chamber
  • Solutions (APB, ATP, PCT, milli-Q, TM)
  • 30 °C incubator with shaking
  • sterile tea spoon
  • mira cloth in funnel (sterile)
  • Glucanex
  • magnet stirrer
  • magnets
  • 50 ml sterile falcon tubes
  • 0.45 µm filters
  • 50 ml syringe
  • centrifuge for falcon tubes

Media

  • Aspergillus transformation buffer (ATB)
  • Aspergillus protoplastation buffer (APB)
  • 500 ml shake flasks
  • YPD media

Procedure

Initiation

  • Streak spore suspension of host strain on YPD plates supplemented with uridine (for this particular fungus) and let grow for a week (there should be black spores!)
  • All solutions should be sterile.

Day 1 (inoculation)

  • Add 95 ml of YPD media supplemented with uridine to a shake flask and transfer 5 ml of the YPD media to a plate with A. niger. Collect conidia and spores from plate by carefully scraping off the conidia using a drigalski (the spores are hydrophobic and would therefore rather just fly around than actually get into suspension so be careful not to make a mess here). This should give a concentration of around 108 spores/100 ml. It is a good idea to make more than one shake flask at a time.
  • Incubate shake flasks at 30 °C, 150 RMP for 48 h.

Day 3 (mycelial harvest)

  • Place the sterile funnel with a mira cloth in to a sterile blue cap bottle and transfer the contents of the shake flasks to the mira cloth (content should be brown and thick).
  • Wash the mycelia using Aspergillus protoplastation buffer (APB) to remove residual glucose from the mycelia (this can inhibit protoplastation). You need to use quite a bit of APB. squeeze out remaining liquid using a sterile spoon. Then, transfer the mycelium to falcon tubes ( ≈2 g per tube => 1 shake flask ≈ 2 falcon tubes).

Protoplastation

  • Add glucanex to APB to get a final concentration of 40 mg glucanex per ml APB and dissolve glucanex via gentle magnetic stirring and no heat.
  • Sterile filter 20 ml of APB+glucanex to each falcon tube using a 0.45 µm filter and a 50 ml syringe (there is a bit of resistance in the filter but that's ok).
  • Shake/incubate enzyme-mycelium mix at 30 °C, 150 RPM for 2-3 h.
  • From now on, whenever you pipette anything with the cells in it, cut of the edge of the pipette tip and CAREFULLY(!) pipette the cells. If you don't do this, they break as they don't have a cell wall to keep them stable.
  • Evaluate the number and quality of protoplasts in a microscope and discard a batch that is too diluted (i.e. < 105 protoplasts/ml). Approved protoplast solutions are then diluted by pouring APB up to 40 ml. and the tubess are balanced. Dilute Aspergillus transformation buffer (ATB) to 1/2x with sterile milli-Q H2O and carefully place 5 ml of this on top of the APB, creating an overlay. Centrifuge samples on rotor settings rotor code Sla-600TC; time: 13 min; Speed: 3000g; Temperatire: 16 °C, Acc: 2, Brake: 2 (NB! due to slow acc and brake, this takes forever!)
  • In the interphase between the two liquids, a halo of white slurry consisting of concentrated protoplasts should be observed. If there is cell wall debris mixed in with the protoplasts, that's ok. They can still be used. Withdraw the protoplasts with a pipette and wash them in a new falcon tube. Add ATB up to 40 ml and pellet the protoplasts at 3000g for 13 min (acc. 2, brake 2). Discard supernatant by decanting.
  • Count protoplasts in microscope by diluting a small sample 1:100.
  • Resuspend protoplasts in 4 ml ATB to obtain concentrated solution.

A quickoverview of the two different transformation protocols

Materials

  • DNA
  • Protoplasts
  • Falcon tubes
  • PCT
  • TM molten agar
  • TM plates
  • ATB

Procedure

Regular protocol

  • Add at MOST 20 uL DNA ( or max 25% of protoplast volume) and 100 uL of protoplasts in a 50 mL falcon tube.
  • Incubate in the falcon tube at RT for at least 30 min.
  • Add 1mL of PCT.
  • Gently mix by gently swirling the tube in a circular motion – careful they are fragile. Do not vortex or pipette mix.
  • Incubate for 5 min at RT.
  • Add 3 mL of ATB.
  • Add 12 mL of molten (40-45 °C) TM agar.
  • Immediately pour mixture directly onto TM plates, and swirl to spread mixture evenly.
  • Let the plates settle for a few minutes and incubate at 37 °C for 4 days.

Quick protocol

  • Add at MOST 25 uL (1500-5000 ng) DNA ( or max 25% of protoplast volume) and 100 uL of protoplasts in a 2 ml Eppendorf tube. 1 uL (100 ng) pac6 as positive control.
  • Add 150 μL PCT with large-nozzle pipette tip.
  • Gently mix by swirling – careful the protoplasts are fragile.
  • Incubate 10-30 min at room temperature.
  • Add 250 μL ATB.
  • Distribute transformation mix on osmotic-stabilized selective media and let the agar absorb the mix before incubating

Protocol for producing a glycerol stock of E. coli adapted by Jacob Mejlsted from Addgene's protocol.

Materials

Consumables

  • 2 mL screw top tube or cryovial

Chemicals

  • 50% glycerol
  • Cell culture

Procedure

Making the stock

  • After having cultivated a culture overnight, add 500 µL culture to 500 µL 50% glycerol in the selected tube
  • The stock can now be frozen at -80°C
    If the stock is repeatedly thawed and frozen, it will reduce the shelf life of the culture

Using the stock

  • To recover bacteria, take a innoculation loop, toothpick or pipete tip and scrape a small amount of bacteria off the top.
  • Transfer this to a plate or a tube with liquid media for growth.
    Normally, media with antibiotics are used. Here Amp and Cam are among the most used.

This guide is to use the biolector.
NB! The machine is very slow - be patient!

Materials

  • biolector

Procedure

  • Turn on the machine (bottom in the back, to the right)
  • Principal window ----> “Monitor”
  • When the lid opens, place the plate in the machine between the metal barrages - it should be firmly secured.
  • For create a new program go to second window “Start …” and follow the steps:
  • Choose new protocol and give it a name (if it is a warm-up program, specify it - the machine needs to warm up for 20-30 min before you add the plate) ----> Next. Names should be written as DDMMYYiGEM_*temperature*_XXXXX
  • Select the type of plate (MTP 48 wells FlowerPlate) ----> Next
  • Choose Layout (48 MTP) ----> Next
  • Select rpm (1000 rpm), temperature and humidity control, and manual (by defect) ----> Next
  • Select the filters to use (Biomass –> Gain 10, PFP –> Gain ?, GFP –> Gain ? ) ----> Next
  • Choose cycle time (30 min for the warm-up program and 3 min (more if several filters are addded) for our program) ----> Start
  • The machine will ask for refilling the deposit with water. Once done, press OK and the program will start running. Be sure to fill up water once a day.
  • When the running is finished, press Stop and save the file in the computer (in the machine, it is saved automatically). You need to press the 'update' button on the computer to get the updated data.
  • In the software go to “Data Management” and select “Transfer the data…”. You can create a new folder or select one already created and press create file. The file will be saved in the folder in cvs format.

By David Faurdal, adapted in part from NEB's one-taq protocol.

The purpose of this protocol is to confirm correct insertion of fragments after assemblies, such as 3A, Gibson, or Golden Gate. As the fragments run on the gel won't be used for cloning purposes, there is no reason to use high-fidelity polymerases on this, just use one-taq.

Materials

  • Transformants from whatever assembly method you fashion
  • Eppendorf tubes
  • Steril toothpicks/inoculation lops/pipette tips for transferring colonies
  • Sterile water
  • LB media with apropriate antibiotics

Procedure

Preparing the template DNA from the transformants:

  • Streak spore suspension of host strain on YPD plates supplemented with uridine (for this particular fungus) and let grow for a week (there should be black spores!)
  • All solutions should be sterile.

Day 1 (inoculation)

  • Add 95 ml of YPD media supplemented with uridine to a shake flask and transfer 5 ml of the YPD media to a plate with A. niger. Collect conidia and spores from plate by carefully scraping off the conidia using a drigalski (the spores are hydrophobic and would therefore rather just fly around than actually get into suspension so be careful not to make a mess here). This should give a concentration of around 108 spores/100 ml. It is a good idea to make more than one shake flask at a time.
  • Incubate shake flasks at 30 °C, 150 RMP for 48 h.

Day 3 (mycelial harvest)

  • Place the sterile funnel with a mira cloth in to a sterile blue cap bottle and transfer the contents of the shake flasks to the mira cloth (content should be brown and thick).
  • Wash the mycelia using Aspergillus protoplastation buffer (APB) to remove residual glucose from the mycelia (this can inhibit protoplastation). You need to use quite a bit of APB. squeeze out remaining liquid using a sterile spoon. Then, transfer the mycelium to falcon tubes ( ≈2 g per tube => 1 shake flask ≈ 2 falcon tubes).

Protoplastation

  • Add glucanex to APB to get a final concentration of 40 mg glucanex per ml APB and dissolve glucanex via gentle magnetic stirring and no heat.
  • Sterile filter 20 ml of APB+glucanex to each falcon tube using a 0.45 µm filter and a 50 ml syringe (there is a bit of resistance in the filter but that's ok).
  • Shake/incubate enzyme-mycelium mix at 30 °C, 150 RPM for 2-3 h.
  • From now on, whenever you pipette anything with the cells in it, cut of the edge of the pipette tip and CAREFULLY(!) pipette the cells. If you don't do this, they break as they don't have a cell wall to keep them stable.
  • Evaluate the number and quality of protoplasts in a microscope and discard a batch that is too diluted (i.e. < 105 protoplasts/ml). Approved protoplast solutions are then diluted by pouring APB up to 40 ml. and the tubess are balanced. Dilute Aspergillus transformation buffer (ATB) to 1/2x with sterile milli-Q H2O and carefully place 5 ml of this on top of the APB, creating an overlay. Centrifuge samples on rotor settings rotor code Sla-600TC; time: 13 min; Speed: 3000g; Temperatire: 16 °C, Acc: 2, Brake: 2 (NB! due to slow acc and brake, this takes forever!)
  • In the interphase between the two liquids, a halo of white slurry consisting of concentrated protoplasts should be observed. If there is cell wall debris mixed in with the protoplasts, that's ok. They can still be used. Withdraw the protoplasts with a pipette and wash them in a new falcon tube. Add ATB up to 40 ml and pellet the protoplasts at 3000g for 13 min (acc. 2, brake 2). Discard supernatant by decanting.
  • Count protoplasts in microscope by diluting a small sample 1:100.
  • Resuspend protoplasts in 4 ml ATB to obtain concentrated solution.

This protocol is the adapted protocol from 223.

Materials

  • Fungal plates (either streaked or 3-point)
  • Drigalski spatula
  • 500 ml shake flasks
  • Counting chamber
  • Solutions (APB, ATP, PCT, milli-Q, TM)
  • 30 °C incubator with shaking
  • sterile tea spoon
  • mira cloth in funnel (sterile)
  • Glucanex
  • magnet stirrer
  • magnets
  • 50 ml sterile falcon tubes
  • 0.45 µm filters
  • 50 ml syringe
  • centrifuge for falcon tubes

Media

  • Aspergillus transformation buffer (ATB)
  • Aspergillus protoplastation buffer (APB)
  • 500 ml shake flasks
  • YPD media

Procedure

Initiation

  • Streak spore suspension of host strain on YPD plates supplemented with uridine (for this particular fungus) and let grow for a week (there should be black spores!)
  • All solutions should be sterile.

Day 1 (inoculation)

  • Add 95 ml of YPD media supplemented with uridine to a shake flask and transfer 5 ml of the YPD media to a plate with A. niger. Collect conidia and spores from plate by carefully scraping off the conidia using a drigalski (the spores are hydrophobic and would therefore rather just fly around than actually get into suspension so be careful not to make a mess here). This should give a concentration of around 108 spores/100 ml. It is a good idea to make more than one shake flask at a time.
  • Incubate shake flasks at 30 °C, 150 RMP for 48 h.

Day 3 (mycelial harvest)

  • Place the sterile funnel with a mira cloth in to a sterile blue cap bottle and transfer the contents of the shake flasks to the mira cloth (content should be brown and thick).
  • Wash the mycelia using Aspergillus protoplastation buffer (APB) to remove residual glucose from the mycelia (this can inhibit protoplastation). You need to use quite a bit of APB. squeeze out remaining liquid using a sterile spoon. Then, transfer the mycelium to falcon tubes ( ≈2 g per tube => 1 shake flask ≈ 2 falcon tubes).

Protoplastation

  • Add glucanex to APB to get a final concentration of 40 mg glucanex per ml APB and dissolve glucanex via gentle magnetic stirring and no heat.
  • Sterile filter 20 ml of APB+glucanex to each falcon tube using a 0.45 µm filter and a 50 ml syringe (there is a bit of resistance in the filter but that's ok).
  • Shake/incubate enzyme-mycelium mix at 30 °C, 150 RPM for 2-3 h.
  • From now on, whenever you pipette anything with the cells in it, cut of the edge of the pipette tip and CAREFULLY(!) pipette the cells. If you don't do this, they break as they don't have a cell wall to keep them stable.
  • Evaluate the number and quality of protoplasts in a microscope and discard a batch that is too diluted (i.e. < 105 protoplasts/ml). Approved protoplast solutions are then diluted by pouring APB up to 40 ml. and the tubess are balanced. Dilute Aspergillus transformation buffer (ATB) to 1/2x with sterile milli-Q H2O and carefully place 5 ml of this on top of the APB, creating an overlay. Centrifuge samples on rotor settings rotor code Sla-600TC; time: 13 min; Speed: 3000g; Temperatire: 16 °C, Acc: 2, Brake: 2 (NB! due to slow acc and brake, this takes forever!)
  • In the interphase between the two liquids, a halo of white slurry consisting of concentrated protoplasts should be observed. If there is cell wall debris mixed in with the protoplasts, that's ok. They can still be used. Withdraw the protoplasts with a pipette and wash them in a new falcon tube. Add ATB up to 40 ml and pellet the protoplasts at 3000g for 13 min (acc. 2, brake 2). Discard supernatant by decanting.
  • Count protoplasts in microscope by diluting a small sample 1:100.
  • Resuspend protoplasts in 4 ml ATB to obtain concentrated solution.

This protocol is the adapted protocol from 223.

Materials

  • Fungal plates (either streaked or 3-point)
  • Drigalski spatula
  • 500 ml shake flasks
  • Counting chamber
  • Solutions (APB, ATP, PCT, milli-Q, TM)
  • 30 °C incubator with shaking
  • sterile tea spoon
  • mira cloth in funnel (sterile)
  • Glucanex
  • magnet stirrer
  • magnets
  • 50 ml sterile falcon tubes
  • 0.45 µm filters
  • 50 ml syringe
  • centrifuge for falcon tubes

Media

  • Aspergillus transformation buffer (ATB)
  • Aspergillus protoplastation buffer (APB)
  • 500 ml shake flasks
  • YPD media

Procedure

Initiation

  • Streak spore suspension of host strain on YPD plates supplemented with uridine (for this particular fungus) and let grow for a week (there should be black spores!)
  • All solutions should be sterile.

Day 1 (inoculation)

  • Add 95 ml of YPD media supplemented with uridine to a shake flask and transfer 5 ml of the YPD media to a plate with A. niger. Collect conidia and spores from plate by carefully scraping off the conidia using a drigalski (the spores are hydrophobic and would therefore rather just fly around than actually get into suspension so be careful not to make a mess here). This should give a concentration of around 108 spores/100 ml. It is a good idea to make more than one shake flask at a time.
  • Incubate shake flasks at 30 °C, 150 RMP for 48 h.

Day 3 (mycelial harvest)

  • Place the sterile funnel with a mira cloth in to a sterile blue cap bottle and transfer the contents of the shake flasks to the mira cloth (content should be brown and thick).
  • Wash the mycelia using Aspergillus protoplastation buffer (APB) to remove residual glucose from the mycelia (this can inhibit protoplastation). You need to use quite a bit of APB. squeeze out remaining liquid using a sterile spoon. Then, transfer the mycelium to falcon tubes ( ≈2 g per tube => 1 shake flask ≈ 2 falcon tubes).

Protoplastation

  • Add glucanex to APB to get a final concentration of 40 mg glucanex per ml APB and dissolve glucanex via gentle magnetic stirring and no heat.
  • Sterile filter 20 ml of APB+glucanex to each falcon tube using a 0.45 µm filter and a 50 ml syringe (there is a bit of resistance in the filter but that's ok).
  • Shake/incubate enzyme-mycelium mix at 30 °C, 150 RPM for 2-3 h.
  • From now on, whenever you pipette anything with the cells in it, cut of the edge of the pipette tip and CAREFULLY(!) pipette the cells. If you don't do this, they break as they don't have a cell wall to keep them stable.
  • Evaluate the number and quality of protoplasts in a microscope and discard a batch that is too diluted (i.e. < 105 protoplasts/ml). Approved protoplast solutions are then diluted by pouring APB up to 40 ml. and the tubess are balanced. Dilute Aspergillus transformation buffer (ATB) to 1/2x with sterile milli-Q H2O and carefully place 5 ml of this on top of the APB, creating an overlay. Centrifuge samples on rotor settings rotor code Sla-600TC; time: 13 min; Speed: 3000g; Temperatire: 16 °C, Acc: 2, Brake: 2 (NB! due to slow acc and brake, this takes forever!)
  • In the interphase between the two liquids, a halo of white slurry consisting of concentrated protoplasts should be observed. If there is cell wall debris mixed in with the protoplasts, that's ok. They can still be used. Withdraw the protoplasts with a pipette and wash them in a new falcon tube. Add ATB up to 40 ml and pellet the protoplasts at 3000g for 13 min (acc. 2, brake 2). Discard supernatant by decanting.
  • Count protoplasts in microscope by diluting a small sample 1:100.
  • Resuspend protoplasts in 4 ml ATB to obtain concentrated solution.

This protocol is the adapted protocol from 223.

Materials

  • Fungal plates (either streaked or 3-point)
  • Drigalski spatula
  • 500 ml shake flasks
  • Counting chamber
  • Solutions (APB, ATP, PCT, milli-Q, TM)
  • 30 °C incubator with shaking
  • sterile tea spoon
  • mira cloth in funnel (sterile)
  • Glucanex
  • magnet stirrer
  • magnets
  • 50 ml sterile falcon tubes
  • 0.45 µm filters
  • 50 ml syringe
  • centrifuge for falcon tubes

Media

  • Aspergillus transformation buffer (ATB)
  • Aspergillus protoplastation buffer (APB)
  • 500 ml shake flasks
  • YPD media

Procedure

Initiation

  • Streak spore suspension of host strain on YPD plates supplemented with uridine (for this particular fungus) and let grow for a week (there should be black spores!)
  • All solutions should be sterile.

Day 1 (inoculation)

  • Add 95 ml of YPD media supplemented with uridine to a shake flask and transfer 5 ml of the YPD media to a plate with A. niger. Collect conidia and spores from plate by carefully scraping off the conidia using a drigalski (the spores are hydrophobic and would therefore rather just fly around than actually get into suspension so be careful not to make a mess here). This should give a concentration of around 108 spores/100 ml. It is a good idea to make more than one shake flask at a time.
  • Incubate shake flasks at 30 °C, 150 RMP for 48 h.

Day 3 (mycelial harvest)

  • Place the sterile funnel with a mira cloth in to a sterile blue cap bottle and transfer the contents of the shake flasks to the mira cloth (content should be brown and thick).
  • Wash the mycelia using Aspergillus protoplastation buffer (APB) to remove residual glucose from the mycelia (this can inhibit protoplastation). You need to use quite a bit of APB. squeeze out remaining liquid using a sterile spoon. Then, transfer the mycelium to falcon tubes ( ≈2 g per tube => 1 shake flask ≈ 2 falcon tubes).

Protoplastation

  • Add glucanex to APB to get a final concentration of 40 mg glucanex per ml APB and dissolve glucanex via gentle magnetic stirring and no heat.
  • Sterile filter 20 ml of APB+glucanex to each falcon tube using a 0.45 µm filter and a 50 ml syringe (there is a bit of resistance in the filter but that's ok).
  • Shake/incubate enzyme-mycelium mix at 30 °C, 150 RPM for 2-3 h.
  • From now on, whenever you pipette anything with the cells in it, cut of the edge of the pipette tip and CAREFULLY(!) pipette the cells. If you don't do this, they break as they don't have a cell wall to keep them stable.
  • Evaluate the number and quality of protoplasts in a microscope and discard a batch that is too diluted (i.e. < 105 protoplasts/ml). Approved protoplast solutions are then diluted by pouring APB up to 40 ml. and the tubess are balanced. Dilute Aspergillus transformation buffer (ATB) to 1/2x with sterile milli-Q H2O and carefully place 5 ml of this on top of the APB, creating an overlay. Centrifuge samples on rotor settings rotor code Sla-600TC; time: 13 min; Speed: 3000g; Temperatire: 16 °C, Acc: 2, Brake: 2 (NB! due to slow acc and brake, this takes forever!)
  • In the interphase between the two liquids, a halo of white slurry consisting of concentrated protoplasts should be observed. If there is cell wall debris mixed in with the protoplasts, that's ok. They can still be used. Withdraw the protoplasts with a pipette and wash them in a new falcon tube. Add ATB up to 40 ml and pellet the protoplasts at 3000g for 13 min (acc. 2, brake 2). Discard supernatant by decanting.
  • Count protoplasts in microscope by diluting a small sample 1:100.
  • Resuspend protoplasts in 4 ml ATB to obtain concentrated solution.

This protocol is the adapted protocol from 223.

Materials

  • Fungal plates (either streaked or 3-point)
  • Drigalski spatula
  • 500 ml shake flasks
  • Counting chamber
  • Solutions (APB, ATP, PCT, milli-Q, TM)
  • 30 °C incubator with shaking
  • sterile tea spoon
  • mira cloth in funnel (sterile)
  • Glucanex
  • magnet stirrer
  • magnets
  • 50 ml sterile falcon tubes
  • 0.45 µm filters
  • 50 ml syringe
  • centrifuge for falcon tubes

Media

  • Aspergillus transformation buffer (ATB)
  • Aspergillus protoplastation buffer (APB)
  • 500 ml shake flasks
  • YPD media

Procedure

Initiation

  • Streak spore suspension of host strain on YPD plates supplemented with uridine (for this particular fungus) and let grow for a week (there should be black spores!)
  • All solutions should be sterile.

Day 1 (inoculation)

  • Add 95 ml of YPD media supplemented with uridine to a shake flask and transfer 5 ml of the YPD media to a plate with A. niger. Collect conidia and spores from plate by carefully scraping off the conidia using a drigalski (the spores are hydrophobic and would therefore rather just fly around than actually get into suspension so be careful not to make a mess here). This should give a concentration of around 108 spores/100 ml. It is a good idea to make more than one shake flask at a time.
  • Incubate shake flasks at 30 °C, 150 RMP for 48 h.

Day 3 (mycelial harvest)

  • Place the sterile funnel with a mira cloth in to a sterile blue cap bottle and transfer the contents of the shake flasks to the mira cloth (content should be brown and thick).
  • Wash the mycelia using Aspergillus protoplastation buffer (APB) to remove residual glucose from the mycelia (this can inhibit protoplastation). You need to use quite a bit of APB. squeeze out remaining liquid using a sterile spoon. Then, transfer the mycelium to falcon tubes ( ≈2 g per tube => 1 shake flask ≈ 2 falcon tubes).

Protoplastation

  • Add glucanex to APB to get a final concentration of 40 mg glucanex per ml APB and dissolve glucanex via gentle magnetic stirring and no heat.
  • Sterile filter 20 ml of APB+glucanex to each falcon tube using a 0.45 µm filter and a 50 ml syringe (there is a bit of resistance in the filter but that's ok).
  • Shake/incubate enzyme-mycelium mix at 30 °C, 150 RPM for 2-3 h.
  • From now on, whenever you pipette anything with the cells in it, cut of the edge of the pipette tip and CAREFULLY(!) pipette the cells. If you don't do this, they break as they don't have a cell wall to keep them stable.
  • Evaluate the number and quality of protoplasts in a microscope and discard a batch that is too diluted (i.e. < 105 protoplasts/ml). Approved protoplast solutions are then diluted by pouring APB up to 40 ml. and the tubess are balanced. Dilute Aspergillus transformation buffer (ATB) to 1/2x with sterile milli-Q H2O and carefully place 5 ml of this on top of the APB, creating an overlay. Centrifuge samples on rotor settings rotor code Sla-600TC; time: 13 min; Speed: 3000g; Temperatire: 16 °C, Acc: 2, Brake: 2 (NB! due to slow acc and brake, this takes forever!)
  • In the interphase between the two liquids, a halo of white slurry consisting of concentrated protoplasts should be observed. If there is cell wall debris mixed in with the protoplasts, that's ok. They can still be used. Withdraw the protoplasts with a pipette and wash them in a new falcon tube. Add ATB up to 40 ml and pellet the protoplasts at 3000g for 13 min (acc. 2, brake 2). Discard supernatant by decanting.
  • Count protoplasts in microscope by diluting a small sample 1:100.
  • Resuspend protoplasts in 4 ml ATB to obtain concentrated solution.